Thermal barrier seal

ABSTRACT

A thermal barrier attachment seal for a gas turbine engine component includes a spine having a first surface and a second surface facing opposite the first surface. A first layer of insulation is provided on the first surface. A second layer of insulation is provided on the second surface to provide a thermal barrier seal between a first gas turbine engine component and a second gas turbine engine component. A fan section for a gas turbine engine is also disclosed.

BACKGROUND OF THE INVENTION

A gas turbine engine includes a fan section that drives air along abypass flow path via a bypass duct defined within a nacelle, while acompressor section drives air along a core flow path for compression andcommunication into a combustor section and subsequent expansion througha turbine section. The fan section comprises a fan case that surrounds afan. The fan case can serve as an attachment point to mount othercomponents within the gas turbine engine. For example, hot componentssuch as a hot duct can be mounted to the fan case via a link and bracketassembly. Traditionally, the bracket for the link has been directlymounted to a fan case boss. This direct mount configuration provides aheat transfer path from the hot duct to the fan case.

However, due to temperature restrictions for the fan case, componentsthat are to be mounted to the fan case are subject to a touchtemperature requirement. As such, it is important to minimize heattransfer from hot components to the fan case via respective attachmentpoints.

SUMMARY OF THE INVENTION

In a featured embodiment, a thermal barrier attachment seal for a gasturbine engine component includes a spine having a first surface and asecond surface facing opposite the first surface. A first layer ofinsulation is provided on the first surface. A second layer ofinsulation is provided on the second surface to provide a thermalbarrier seal between a first gas turbine engine component and a secondgas turbine engine component.

In another embodiment according to the previous embodiment, the firstand second layers of insulation comprise MIN-K® insulation material.

In another embodiment according to any of the previous embodiments, athird layer of insulation material is provided over the first layer ofinsulation and a fourth layer of insulation material is provided overthe second layer of insulation.

In another embodiment according to any of the previous embodiments, thethird and fourth layers of insulation material comprise a siliconeimpregnated cloth that is wrapped around the spine and the first andsecond layers of insulation such that outwardly facing edges of thespine and the first and second layers of insulation are covered by thesilicone impregnated cloth to provide the seal.

In another embodiment according to any of the previous embodiments, thespine has a first thickness extending between the first and secondsurfaces, the first and second layers each have a second thickness, andthe third and fourth layers each have a third thickness, and wherein thesecond thickness is at least two times the third thickness.

In another embodiment according to any of the previous embodiments, thespine has a first thickness extending between the first and secondsurfaces, the first and second layers each have a second thickness, andthe third and fourth layers each have a third thickness, and wherein thefirst thickness is at least one and a half times the third thickness.

In another embodiment according to any of the previous embodiments, thesecond thickness is at least two times the third thickness.

In another embodiment according to any of the previous embodiments, thespine comprises an elongated body having a first washer integrallyformed at a first end of the elongated body and a second washerintegrally formed at a second end of the elongated body.

In another embodiment according to any of the previous embodiments, theelongated body and the first and second washers are formed from analuminum material.

In another embodiment according to any of the previous embodiments, thefirst and second washers comprise split lock washers.

In another embodiment according to any of the previous embodiments, thethermal barrier seal has a first surface that is configured to abutdirectly against the first gas turbine engine component and a secondsurface that is configured to abut directly against the second gasturbine engine component.

In another embodiment according to any of the previous embodiments, thefirst gas turbine engine component comprises a heated component and thesecond gas turbine engine component comprises a fan case, and whereinthe thermal barrier seal includes a first opening for a first fastenerto attach the heated component to the fan case and a second opening fora second fastener to attach the heated component to the fan case.

In another embodiment according to any of the previous embodiments, anouter surface of the thermal barrier seal is recessed to fit over a fancase boss extending outwardly from the fan case.

In another featured embodiment, a fan section for a gas turbine engineincludes a fan case configured to surround a fan, wherein the fan caseincludes at least one mount interface. A component is configured to beattached to the mount interface. A thermal barrier seal attaches thecomponent to the fan case via the mount interface. The thermal barrierseal comprises an elongated spine body having a first surface and asecond surface facing opposite the first surface, the elongated spinebody having a first washer integrally formed at a first end of theelongated spine body and a second washer integrally formed at a secondend of the elongated spine body. A first layer of insulation is providedon the first surface. A second layer of insulation is provided on thesecond surface to provide a thermal barrier at the mount interfacebetween the component and the fan case.

In another embodiment according to the previous embodiment, the mountinterface comprises a fan case boss that extends outwardly from anexternal surface of the fan case, and wherein the thermal barrier sealis configured to attach the component to the fan case boss via abracket.

In another embodiment according to any of the previous embodiments, athird layer of insulation material is provided on top of the first layerof insulation and a fourth layer of insulation material is provided ontop of the second layer of insulation.

In another embodiment according to any of the previous embodiments, thefirst and second layers of insulation comprise MIN-K® insulationmaterial, and wherein the third and fourth layers of insulation materialcomprise a silicone impregnated cloth that is wrapped around theelongated spine body and the first and second layers of insulation suchthat outwardly facing edges of the elongated spine body and the firstand second layers of insulation are covered by the silicone impregnatedcloth.

In another embodiment according to any of the previous embodiments, thefan case is comprised of a composite material, and wherein the elongatedspine body is comprised of a rigid metallic material.

In another embodiment according to any of the previous embodiments, theelongated spine body has a first thickness extending between the firstand second surfaces, the first and second layers each have a secondthickness, and the third and fourth layers each have a third thickness,and wherein the first thickness is at least one and a half times thethird thickness, and wherein the second thickness is at least two timesthe third thickness.

In another embodiment according to any of the previous embodiments, thefirst and second washers each include a center opening, and including afirst fastener extending through the center opening of the first washerand a second fastener extending through the center opening of the secondwasher, wherein the first and second fasteners fix the component to afan case boss extending outwardly from the fan case.

The foregoing features and elements may be combined in any combinationwithout exclusivity, unless expressly indicated otherwise.

These and other features may be best understood from the followingdrawings and specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of one example of a gas turbineengine.

FIG. 2 is a top view of an attachment mechanism incorporating thesubject invention.

FIG. 3 is a perspective view of the mechanism of FIG. 2.

FIG. 4 is a perspective of the mechanism of FIG. 2 with a thermalisolation barrier.

FIG. 5 is a schematic exploded side view of material stack up of themechanism and thermal isolation barrier of FIG. 4.

FIG. 6 is a schematic side view of the subject attachment mechanismattaching a component to a fan case boss.

FIG. 7 is an exploded view of the attachment mechanism of FIG. 4 inrelation to the fan case boss.

FIG. 8 is a bottom view of the attachment mechanism of FIG. 7.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct defined within a nacelle 15, while the compressor section 24drives air along a core flow path C for compression and communicationinto the combustor section 26 then expansion through the turbine section28. Although depicted as a two-spool turbofan gas turbine engine in thedisclosed non-limiting embodiment, it should be understood that theconcepts described herein are not limited to use with two-spoolturbofans as the teachings may be applied to other types of turbineengines including three-spool architectures.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided, and the location of bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a first (or low) pressure compressor 44 and afirst (or low) pressure turbine 46. The inner shaft 40 is connected tothe fan 42 through a speed change mechanism, which in exemplary gasturbine engine 20 is illustrated as a geared architecture 48 to drivethe fan 42 at a lower speed than the low speed spool 30. The high speedspool 32 includes an outer shaft 50 that interconnects a second (orhigh) pressure compressor 52 and a second (or high) pressure turbine 54.A combustor 56 is arranged in exemplary gas turbine 20 between the highpressure compressor 52 and the high pressure turbine 54. A mid-turbineframe 57 of the engine static structure 36 is arranged generally betweenthe high pressure turbine 54 and the low pressure turbine 46. Themid-turbine frame 57 further supports bearing systems 38 in the turbinesection 28. The inner shaft 40 and the outer shaft 50 are concentric androtate via bearing systems 38 about the engine central longitudinal axisA which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 whichare in the core airflow path C. The turbines 46, 54 rotationally drivethe respective low speed spool 30 and high speed spool 32 in response tothe expansion. It will be appreciated that each of the positions of thefan section 22, compressor section 24, combustor section 26, turbinesection 28, and fan drive gear system 48 may be varied. For example,gear system 48 may be located aft of combustor section 26 or even aft ofturbine section 28, and fan section 22 may be positioned forward or aftof the location of gear system 48.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10), thegeared architecture 48 is an epicyclic gear train, such as a planetarygear system or other gear system, with a gear reduction ratio of greaterthan about 2.3 and the low pressure turbine 46 has a pressure ratio thatis greater than about five. In one disclosed embodiment, the engine 20bypass ratio is greater than about ten (10:1), the fan diameter issignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 has a pressure ratio that is greater thanabout five 5:1. Low pressure turbine 46 pressure ratio is pressuremeasured prior to inlet of low pressure turbine 46 as related to thepressure at the outlet of the low pressure turbine 46 prior to anexhaust nozzle. The geared architecture 48 may be an epicycle geartrain, such as a planetary gear system or other gear system, with a gearreduction ratio of greater than about 2.3:1. It should be understood,however, that the above parameters are only exemplary of one embodimentof a geared architecture engine and that the present invention isapplicable to other gas turbine engines including direct driveturbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8 Mach andabout 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft, withthe engine at its best fuel consumption—also known as “bucket cruiseThrust Specific Fuel Consumption (‘TSFC’)”—is the industry standardparameter of lbm of fuel being burned divided by lbf of thrust theengine produces at that minimum point. “Low fan pressure ratio” is thepressure ratio across the fan blade alone, without a Fan Exit Guide Vane(“FEGV”) system. The low fan pressure ratio as disclosed hereinaccording to one non-limiting embodiment is less than about 1.45. “Lowcorrected fan tip speed” is the actual fan tip speed in ft/sec dividedby an industry standard temperature correction of [(Tram ° R)/(518.7°R)]⁵. The “Low corrected fan tip speed” as disclosed herein according toone non-limiting embodiment is less than about 1150 ft/second.

FIGS. 2-3 show an attachment mechanism 60 comprising a thermal barrierseal that is used to connect a first engine component to anothercomponent. In one example, the attachment mechanism 60 is used toconnect an engine component to the fan case or fan nacelle 15 of the fansection 22 (FIG. 1). The attachment mechanism 60 includes a spinecomprising an elongated body 62 having at least first 64 and second 66ends. A first attachment feature 68 is formed at the first end 64 and asecond attachment feature 70 is formed at the second end 66. The first68 and second 70 attachment features define attachment points that areused to attach the two engine components together. This will bediscussed in greater detail below.

In one example, the elongated body 62 comprises a straight, flat bar orspine body that has the first 68 and second 70 attachment featuresformed on opposing ends. In one example, the elongated body 62 iscomprised of a rigid metallic material. One type of material that couldbe used for the body 62 is aluminum, for example.

As shown in FIGS. 2-3, the first 68 and second 70 attachment featurescomprise first and second washers that are integrally formed with theelongated body 62 as a single-piece structure. Each washer comprises aring-shaped body 72. In one example, the ring-shaped body 72 includes asplit 74 such that the washers comprise split lock washers. The split 74separates the ring-shaped body 72 into first 76 and second 78 curvedportions. The first 76 and second 78 curved portions have respectivefirst 80 and second 82 upper surfaces and first 84 and second 86 lowersurfaces that face opposite from the upper surfaces 80, 82. As shown inFIGS. 3, when the washers are in an uninstalled configuration, the first80 and second 82 upper surfaces are non-coplanar. The first 84 andsecond 86 lower surfaces are also non-coplanar when in the uninstalledposition.

As shown in FIG. 4, a thermal isolation barrier 88 surrounds theelongated body 62 and the first 68 and second 70 attachment features.The material used to form the thermal isolation barrier 88 is shown inFIG. 5. The elongated body 62 has an upper surface 90 and a lowersurface 92. The thermal isolation barrier 88 comprises a first layer ofinsulation 94 in direct contact with the upper surface 90 and a secondlayer of insulation 96 in direct contact with the lower surface 92. Athird layer of insulation material 98 is in direct contact with thefirst layer of insulation 94 and a fourth layer of insulation material100 is in direct contact with the second layer of insulation 96.

In one example, the first 94 and second 96 layers of insulation materialcomprise MIN-K® microporous insulation. MIN-K® provides good thermalmanagement performance in combination with having a low weight. TheMin-K® material used for the first layer of insulation 94 and secondlayer of insulation 96 is flexible and can be made from board, tape,felt, or quilt material. The Min-K® material has low thermalconductivity, provides compression resistance and is lightweight.

In one example, the third 98 and fourth 100 layers of insulationmaterial comprise a silicone impregnated cloth. The cloth is wrappedaround the stack up of the layers of insulation material 94, 96 and theelongated body 62 with the first 68 and second 70 attachment features.This wrapped structure thus encloses the elongated body 62 and the first68 and second 70 attachment features to form a sealed structure thatincludes center openings 102 that extend through each washer of thefirst 68 and second 70 attachment features.

In one example, the MIN-K® insulation material of the first 94 andsecond 96 layers is two times a thickness of the silicone impregnatedcloth used for the third 98 and fourth 100 layers, and the elongatedspine body 62 is one and a half times the thickness of the siliconeimpregnated cloth. The silicone impregnated cloth wraps around the stackof MIN-K® insulation layers and the elongated spine, and will stiffen asthe cloth sets.

FIG. 6 shows an example of the attachment mechanism 60 being used toattach an engine component 110 to a fan case 112. The fan case 112surrounds the fan 42 (FIG. 1) and includes at least one mount interface114. The engine component 110 is configured to be attached to the mountinterface 114 via the attachment mechanism 60. In one example, the mountinterface 114 comprises a fan case boss 114 a that extends outwardlyfrom an external surface 116 of the fan case 112 and the enginecomponent 110 comprises a hot duct that is secured to the fan case bossvia a bracket 118 and linkage 120.

FIG. 7 shows the stack up of the thermal barrier seal attachmentmechanism 60 in relation to the fan case boss 114 a. The elongated body62 is sandwiched between the first 94 and second 96 layers of insulationmaterial. Then the cloth is wrapped around the elongated body 62 and thefirst 94 and second 96 layers of insulation material to form the third98 and fourth 100 layers of insulating material. It should be understoodthat while the third 98 and fourth 100 layers are shown separately inFIG. 7 they are from a common sheet of cloth material that is wrappedaround the elongated body 62 and the first 94 and second 96 layers ofinsulation material. The layers 98/100 are only shown separately forillustrative purposes such that the elongated body 62 and the first 94and second 96 layers of insulation material can be seen clearly in thestack up of FIG. 7.

Thus, as the sheet of impregnated cloth material that forms the third 98and fourth 100 layers is wrapped around the elongated body 62 and thefirst 94 and second 96 layers, all exposed edges 130 about an outerperiphery of the elongated body 62 are covered. Additionally, allexposed edges 132 about an outer periphery of the first 94 and second 96layers are covered by the sheet of impregnated cloth material. Thisforms a sealed thermal barrier structure through which the centeropenings 102 extend to receive fasteners as discussed below.

FIG. 8 shows a bottom surface 138 of the thermal barrier seal attachmentmechanism 60. This bottom surface 138 is cupped or recessed such thatthe thermal barrier seal can snuggly fit over the fan case boss 114 a asshown in FIG. 4.

The thermal barrier seal attachment mechanism 60 with the thermalisolation barrier 88 is sandwiched between the bracket 118 and the mountinterface 114. As discussed above, the first and second washers thatcomprise the first 68 and second 70 attachment features have a centeropening 102. A first fastener 122 extends through the center opening 102of the first washer and a second fastener 124 extends through the centeropening 102 of the second washer. The first 122 and second 124 fastenerscompress against the lock washers such that the lock washers exert aforce on the head of the fasteners via compression to prevent thefasteners from backing out.

In one example, the fan case 112 is comprised of a composite material.The composite fan case 112 and fan case boss of the mount interface 114are subject to temperature restrictions such that components 110 thatanchor to the fan case boss are required to meet touch temperaturerestrictions. The subject attachment mechanism 60 provides a thermalisolation barrier 88 to prevent heat from hot engine components beingtransferred to the fan case 112 via attachment points. As discussedabove, the thermal isolation barrier 88 is comprised of MIN-K®insulation material wrapped with an impregnated silicone cloth. Foradded rigidity at the attachment points, the attachment mechanism 60includes an elongated spine body 62 with integrated lock washers suchthat the fasteners 122, 124 pass through the attachment mechanism 60 andthe thermal isolation barrier 88 to make sure the torque on the thermalbarrier washer remains constant over time.

Although embodiments of this invention has been disclosed, a worker ofordinary skill in this art would recognize that certain modificationswould come within the scope of this invention. For that reason, thefollowing claims should be studied to determine the true scope andcontent of this invention.

1. A thermal barrier attachment seal for a gas turbine engine componentcomprising: a spine having a first surface and a second surface facingopposite the first surface; a first layer of insulation provided on thefirst surface; and a second layer of insulation provided on the secondsurface to provide a thermal barrier seal between a first gas turbineengine component and a second gas turbine engine component.
 2. Thethermal barrier seal according to claim 1 wherein the first and secondlayers of insulation comprise MIN-K® insulation material.
 3. The thermalbarrier seal according to claim 1 including a third layer of insulationmaterial provided over the first layer of insulation and a fourth layerof insulation material provided over the second layer of insulation. 4.The thermal barrier seal according to claim 3 wherein the third andfourth layers of insulation material comprise a silicone impregnatedcloth that is wrapped around the spine and the first and second layersof insulation such that outwardly facing edges of the spine and thefirst and second layers of insulation are covered by the siliconeimpregnated cloth to provide the seal.
 5. The thermal barrier sealaccording to claim 3 wherein the spine has a first thickness extendingbetween the first and second surfaces, the first and second layers eachhave a second thickness, and the third and fourth layers each have athird thickness, and wherein the second thickness is at least two timesthe third thickness.
 6. The thermal barrier seal according to claim 3wherein the spine has a first thickness extending between the first andsecond surfaces, the first and second layers each have a secondthickness, and the third and fourth layers each have a third thickness,and wherein the first thickness is at least one and a half times thethird thickness.
 7. The thermal barrier seal according to claim 6wherein the second thickness is at least two times the third thickness.8. The thermal barrier seal according to claim 1 wherein the spinecomprises an elongated body having a first washer integrally formed at afirst end of the elongated body and a second washer integrally formed ata second end of the elongated body.
 9. The thermal barrier sealaccording to claim 8 wherein the elongated body and the first and secondwashers are formed from an aluminum material.
 10. The thermal barrierseal according to claim 8 wherein the first and second washers comprisesplit lock washers.
 11. The thermal barrier seal according to claim 1wherein the thermal barrier seal has a first surface that is configuredto abut directly against the first gas turbine engine component and asecond surface that is configured to abut directly against the secondgas turbine engine component.
 12. The thermal barrier seal according toclaim 1 wherein the first gas turbine engine component comprises aheated component and the second gas turbine engine component comprises afan case, and wherein the thermal barrier seal includes a first openingfor a first fastener to attach the heated component to the fan case anda second opening for a second fastener to attach the heated component tothe fan case.
 13. The thermal barrier seal according to claim 12 whereinan outer surface of the thermal barrier seal is recessed to fit over afan case boss extending outwardly from the fan case.
 14. A fan sectionfor a gas turbine engine comprising: a fan case configured to surround afan, wherein the fan case includes at least one mount interface; acomponent configured to be attached to the mount interface; and thermalbarrier seal to attach the component to the fan case via the mountinterface, the thermal barrier seal comprising an elongated spine bodyhaving a first surface and a second surface facing opposite the firstsurface, the elongated spine body having a first washer integrallyformed at a first end of the elongated spine body and a second washerintegrally formed at a second end of the elongated spine body, a firstlayer of insulation provided on the first surface, and a second layer ofinsulation provided on the second surface to provide a thermal barrierat the mount interface between the component and the fan case.
 15. Thefan section according to claim 14, wherein the mount interface comprisesa fan case boss that extends outwardly from an external surface of thefan case, and wherein the thermal barrier seal is configured to attachthe component to the fan case boss via a bracket.
 16. The fan sectionaccording to claim 14, including a third layer of insulation materialprovided on top of the first layer of insulation and a fourth layer ofinsulation material provided on top of the second layer of insulation.17. The fan section according to claim 16, wherein the first and secondlayers of insulation comprise MIN-K® insulation material, and whereinthe third and fourth layers of insulation material comprise a siliconeimpregnated cloth that is wrapped around the elongated spine body andthe first and second layers of insulation such that outwardly facingedges of the elongated spine body and the first and second layers ofinsulation are covered by the silicone impregnated cloth.
 18. The fansection according to claim 17, wherein the fan case is comprised of acomposite material, and wherein the elongated spine body is comprised ofa rigid metallic material.
 19. The fan section according to claim 16,wherein the elongated spine body has a first thickness extending betweenthe first and second surfaces, the first and second layers each have asecond thickness, and the third and fourth layers each have a thirdthickness, and wherein the first thickness is at least one and a halftimes the third thickness, and wherein the second thickness is at leasttwo times the third thickness.
 20. The fan section according to claim16, wherein the first and second washers each include a center opening,and including a first fastener extending through the center opening ofthe first washer and a second fastener extending through the centeropening of the second washer, wherein the first and second fasteners fixthe component to a fan case boss extending outwardly from the fan case.